Predictive factors and early outcome of wake-up stroke: a retrospective case series study

Objective To investigate the predictive factors and early outcome in patients with wake-up stroke. Methods Consecutive inpatients with acute ischemic stroke were collected. According to the time of onset, they were divided into either a wake-up stroke group or a non-wake-up stroke group, the demographic and baseline clinical data were compared between the two groups. They were also divided into either an unfavorable outcome group (≥2 points) or a favorable outcome group (0-1) according to the modified Rankin Scale (mRS) scores, amd the demographic and baseline clinical data were compared between the two groups. Results A total of 420 patients with acute ischemic stroke were enrolled, including 103 patients (24.5%) with wake-up stroke and 317 (75.5%) with non-wake-up stroke. Univariate analysis showed that the proportion of large atherosclerotic stroke (23.3% vs.34.7%; χ2=4.650, P=0.031) in the wake-up stroke group was significantly lower than that in the non-wake-up stroke group, while the systolic blood pressure (155.1±19.6 mmHg vs.150.4±20.9 mmHg, 1 mmHg=0.133 kPa; t=2.013, P=0.045), National Institutes of Health Stroke Scale (NIHSS) scores (median [interquartile range], 10.0[5.0-14.0]vs. 7.0[4.5-10.0]; Z=-2.648, P=0.008) and the proportions of small vessel occlusion stroke (21.4% vs.11.0%; χ2=7.056, P=0.008), and atrial fibrillation (25.2% vs.11.8%; χ2=5.874, P=0.015) in the wake-up stroke group were significantly higher than those in the non-wake-up stroke group. Multivariate logistic regression analysis showed that high baseline NIHSS score was an independent predictive factor (odds ratio [OR] 1.075, 95% confidence interval [CI] 1.023-1.130; P=0.004), while prior stroke or transient ischemic attack (OR 0.562, 95% CI 0.327~0.969; P=0.038) and large atherosclerotic stroke were independently associated with non-wake-up stroke. There were 228 patients (54.3%) with favorable outcome and 192 (45.7%) with unfavorable outcome among 420 patients with acute ischemic stroke. Univariate analysis showed that the proportions of wake-up stroke (31.2% vs.18.9%; χ2=8.645, P=0.003) and atrial fibrillation (24.0% vs.11.8%; χ2=10.655, P=0.001), and baseline NIHSS scores (11.0[9.0~14.0] vs.5.0[2.0~7.0]; Z=-15.335, P<0.001) in the unfavorable outcome group were significantly higher than those in the favorable outcome group. Multivariate logistic regression analysis showed that high NIHSS scores was independently associated with unfavorable outcome (OR 2.011, 95% CI 1.753-2.309; P<0.001), while wake-up stroke was not independently associated with unfavorable outcome (OR 1.694, 95% CI 0.779-3.683; P=0.183). Conclusions The high NIHSS scores are the predictive factors for wake-up stroke and early unfavorable outcome in patients with acute ischemic stroke. Wake-up stroke is not associated with early unfavorable outcome in patients with acute ischemic stroke. Key words: Stroke; Brain Ischemia; Wakefulness; Risk Factors; Prognosis